Meb is going to make some big money at New York and Boston to run the marathons in November and April, 2015 respectively. Then, he is going to become a MASTERS runner next May and he'll continue to make some good prize money competing in that division (as well as the overall).
Perhaps Meb does not need the prize money or appearance fees going forward thanks to the Boston win and the efforts by Hawi to secure sponsorships and other income-deriving possibilities. I could also see Meb having some difficulty re-focusing on the training after winning at Boston, but still, he has come back so many times in the past and it's easy to say he's 'reached all he could' - but we could have said that after NYC (and some in fact did).
No idea what the announcement is, but a retirement anytime soon would be a shock.